The kilderkin is an old English unit of volume equal to half a barrel or two firkins. It was used as standard size for brewery

Brewery

A brewery is a dedicated building for the making of beer, though beer can be made at home, and has been for much of beer's history. A company which makes beer is called either a brewery or a brewing company....

 casks. The word kilderkin comes from Dutch for a small cask. The kilderkin has historically been in the general range of 16 to 18 gallons. Based on the current imperial barrel of 36 gallons the following conversions are possible.

1 kilderkin	= ½ barrel
	= 2 firkins
	= 18 imperial gallons
	= 81.82962 litre Litre pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre... s
	≈2.890 cubic feet